WECC REMTF (Renewable Energy Modeling Task Force) November16, 2016 MeetingMinutesRev.1 (12-08-16)
1.“Help with REMTF Dynamic Models” WECC Website (Spencer Tacke All),
Have made some progress towards establishing the location on the WECC website. The personnel contact information (i.e., the four software vendor contacts and modeling contact) will be in one section, and the three subject areas (i.e.,PV, Wind, & Energy Storage) will have their own sections with related documents. We are also trying to add a questions section, where questions can be posed , and the answers displayed, and both stored for member reference.
2. Experience with Model Validation of Renewable Energy Systems document
(Pouyan Pourbeik).
Pouyan Pourbeik (PEACE)has started a document that he presented to the group. It documents various experiences with wind and PV generation model validation. There are some examples in the document, which remain to be completed with text (and more can be added by the REMTF members), and explanations of some of the existing examples are still needed. For now the document is an experience document, and more time and validation experience is needed before this document can become a fully-fledged guide. Pouyan encouraged everyone to pitch in who is interested.
3. Final Update on REPC_B Model (REPC_B) (Pouyan Pourbeik)
Pouyan Pourbeik (PEACE) explained that the slight differences in response for this model across the four software platforms can be explained by the fact that the impedance of the generator was not accounted for the same way (specifically, the generator model reactance parameter Xe is not currently being used in Siemens PTI PSS®E software for the REGC_A dynamic model). The impedance Xe was not defined in the original model specification, it was latter introduced by GE in GE PSLFTM for the purpose of compatibility between the generic model and GE’s equipment specific model. Thus, some of the software platforms use it and others do not. A new REGC_B model will be developed to have a voltage source representation with both Re and Xe and will be consistently implemented across all the commercial tools to address this issue.
- Energy Storage Dynamic Modeling Guideline Document ( Shengli Huang-PSE,
Bo Gong-Columbia Grid).
The completed draft document was sent out for review and comment to the
REMTF members a couple of weeks prior to the Meeting, but to date no
comments have been received. Shengli and Bo have done a fine job, but would
like to receive comments from the members. This document formalizes the
development and model testing of our latest approved model, REEC_C, for
energy storage. The REMTF members at the Meeting agreed to review it by the
end of the year, and Spencer will also forward the document on to the MVWG
for their members input, too.
5. Placing an Energy Storage Model (REEC_C) in the CMPLDW (Bill Price(G.E.), All).
Bill was not able to join the meeting, but the REMTF discussed the issue of importing various models, in general, into the DER (Distributed Energy Resource) slot currently allocated in the CMPLDW2 model(e.g. PVD1). Bill had explained to Spencer via e-mail that once the modular structure CMPLDW2 model is approved, then requests for which models (e.g., simplified REEC_C) to provide in the DER slot can be accepted. The advantage of the new CMPLDW2 modular structure is that no modification will be required to the main module when new sub-component models, such as PVD1 or a simplified REEC_C, etc., are added. Need further discussion with Bill Price and Hamodi Hindi (LMTF Chair) to clarify and resolve.
6. Update on DOE (U.S. Dept. of Energy) Project on Control of Distributed Solar
Plants—Ray Byrne (Sandia National Laboratories)
Ray Byrne and Felipe Wilches-Bernal made a very interesting presentation on the communication latency issues involved in control of large distributed solar PV generating plants. The concept of feed-forward control in response to other system generation and load changes was presented, in an attempt to capitalize on the very fast control response of a PV inverter based system. The impact of various magnitudes of communication delays was studied in the PV distributed system response to system disturbances, and the potential benefits and dangers of the feed-forward control on both transmission and distribution systems was presented. More work by Sandia will be forthcoming on this subject.
7. PVD2 Model Development--Specification (Pouyan Pourbeik).
Pouyan (PEACE) presented his proposed specification (attached) on what was to be an enhanced version of the existing PVD1 model, used for distribution system PV generators. However, Pouyan’s approach was to take the large-scale generic PV Model (i.e., REGC_A, REEC_B, REPC_A, LHVRT and LHFRT) and simplify and reduce it into a single model appropriate for a more complete PV distribution system model. As the discussion evolved during the Meeting, it became apparent that with adjustment of some parameters, this new PVD2 model could represent a simplified energy storage model and a simplified wind generation plant, too. Hence the name was changed to DER_A (Distributed Energy Resource A). Pouyan will make the changes to his original specificationand e-mail it to Spencer, and then bring it back to the REMTF at our March 2017 Meeting for approval (attached).
8. NERC Standard MOD-026 &MOD-027 Model Validation for Solar PV—Vladimir Chadliev, (First Solar, Tempe, AZ)
Vladimir presented very detailed information on some solar PV generating plant model validation work First Solar has recently completed on a 250 MW PV plant.
The Plant second generation model parameters were tuned using the PSLF software for the simulation comparison with PMU data, that was taken at 60 samples per second. Because of the high sampling rate (i.e., 30 samples per second would have been sufficient), the BPA-PNNL PPMV software tool couldn’t be used because too much data was recorded and exceeded the 15998 records limit. Four different test scenarios were used: Over-Frequency, Under-Frequency, and two power factor tests at 50% and 90% of rated output. There was an excellent match between the recorded PMU data response and the simulation. Vladimir indicated he would present more on First Solar PV projects that also provide ancillary services, at the March 2017 REMTF Meeting.
9. BPA Experience with Type 4 Wind Power Plant Model Validation using PMU Data—Dmitry Kosterev (BPA)
There was no presentation or discussion on this topic.
10. Standard DLL (Dynamic Link Library) Interfaces for User-Written Models----Samer
El Itani (SENVION Wind Energy Solutions).
Samer El Itani of Senvion Wind Energy talked about the development of standard DLL (Dynamic Link Library) interfaces for user written models. The concept is really the application of the same DLL model in all software environments, where it embeds into different software like a common user model. This would allow for more extensive utilization of user written custom models, if and when necessary. The key point here is that this concept would allow a cleaner and more portable (across software platforms) means of using vendor-specific and user-written models when they are needed (e.g. detailed local studies related to grid interactions). It is NOT intended in anyway of replacing the need for open and public generic models, which are a requirement under the WECC modeling guidelines and the NERC MOD 32 standard.
Before the next REMTF Meeting in March 2017, we need to get feedback from all the software vendors if they are willing to attempt to develop a standard DLL interface. The general consensus was that more equipment vendors need to come to the table to request this in order to give the impetus for software vendors to consider it.
11. Low Short-Circuit Ratio System Generator/Convertor Model (REGC_B)—(Pouyan Pourbeik/ All)
To improve the numerical stability of the dynamic renewable energy models when they are used in low SCR (Short Circuit Ratio) or weak systems, we need to develop a new renewable energy generator / converter model (REGC_B), which will model the generator / converter interface with the grid as a voltage source instead of a current source (as is presently done). Pouyan presented this concept of an REPC_B model based on a paper published by Deepak (D. Ramasubramanian, Z. Yu, R. Ayyanar, V. Vittal and J. M. Undrill “Converter Model for Representing Converter Interfaced Generation in Large Scale Grid Simulations” IEEE Transactions on Power Systems, April 6, 2016). In that paper, Fig. 1 and Equations (1) depict the controlled voltage source converter model for positive sequence simulations. A proposed specification for the REGC_B model was shown in the slides presented. It will be further discussed by the REMTF and at the March 2017 REMTF Meeting.
12. New Module for Inertia Based Fast-Frequency Response for Wind Turbine
Generators—(Pouyan Pourbeik / ALL)
Pouyan discussed the possible need for a new module to allow for inertia based fast-frequency response emulation (or “synthetic inertia”), which is presently offered by numerous major wind turbine generator manufacturers. Apparently, based on Hongtao Ma’s (SIEMENS Wind) Nov. 2015 and March 2016 presentations, there is a demand for this function in the Hydro Quebec Area (and now possibly in ERCOT), Hawaii, and Puerto Rico. The challenge in developing a generic model for this behavior is that each manufacturer’s emulation of the “synthetic inertia” response is very different. So some common understanding/agreement is needed before a generic model can be developed.
The next REMTF / MVWG Meetings will be March 14-16, 2017 in Salt Lake City, Utah.